In the related art, there are attempts to control the traveling of an individual vehicle to improve traffic flow on a road and to reduce congestion. For example, Patent Literature 1 describes a congestion prevention device which, for the sake of preventing the occurrence of congestion before happens, acquires information indicating that a congestion factor is present on a road on which an host vehicle travels, acquires information indicating the operation of the host vehicle, determines whether or not the operation of the host vehicle is an operation which induces congestion corresponding to the congestion factor, and, when the operation of the host vehicle is an operation which induces congestion, performs driving support for suppressing the occurrence of congestion.